Resin composition, and method for producing the same

ABSTRACT

A resin composition having excellent impact resistance and heat resistance, comprising a poly-3-hydroxybutyrate, and a core-shell latex rubber comprising an acrylic rubber and/or silicone-acrylic rubber copolymer as a core component and polymethyl methacrylate as a shell component, or a specific thermoplastic polyurethane, is disclosed. The resin composition satisfies the following requirements (c) and (d): (c) a crystallization temperature when heated from room temperature to 180° C. at a temperature rising rate of 80° C./min by a differential scanning calorimeter, maintained at 180° C. for 1 minute, and then cooled at a temperature lowering rate of 10° C./min is 110-170° C.; and (d) a weight average molecular weight (Mw) in terms of polystyrene conversion when a chloroform soluble component is measured with a gel permeation chromatography is 100,000-3,000,000.

FIELD OF THE INVENTION

The present invention relates to a resin composition comprising apoly-3-hydroxybutyrate polymer, and a core-shell latex rubber or athermoplastic polyurethane, and a method for producing the resincomposition. More particularly, the present invention relates to apoly-3-hydroxybutyrate polymer resin composition having excellent impactresistance and heat resistance, and a method for producing the resincomposition.

BACKGROUND ART

Poly-3-hydroxybutyrate polymers are obtained using plants as a rawmaterial, and therefore are recently noted as a material having smallenvironmental load. However, the poly-3-hydroxybutyrate polymers havethe problem of having poor impact resistance.

To overcome this problem, a method of mixing polycaprolactone orpolybutyrene succinate resin is proposed as described in, for example,JP-A-9-194281 and JP-A-11-323141.

However, in the method of mixing a different kind of polymer as proposedin the above-described patent publications, a composition thus obtaineddoes not have sufficient impact resistance, and further has poor heatresistance.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above-describeddisadvantages in the prior art.

Accordingly, one object of the present invention is to provide a resincomposition having excellent heat resistance and impact resistance,comprising a poly-3-hydroxybutyrate polymer, and a core-shell latexrubber or a thermoplastic polyurethane.

Another object of the present invention is to provide a method forproducing the resin composition.

As a result of extensive investigations to overcome the disadvantages inthe prior art, it has been found that a resin composition comprising apoly-3-hydroxybutyrate polymer, and a specific core-shell latex rubberor a specific thermoplastic polyurethane exhibits excellent impactresistance and heat resistance. The present invention has been completedbased on this finding.

According to the present invention, there is provided a resincomposition comprising:

50-99% by weight of a poly-3-hydroxybutyrate polymer, and

50-1% by weight of i) a core-shell latex rubber comprising an acrylicrubber and/or a silicone-acrylic rubber copolymer as a core component,and a polymethyl methacrylate as a shell component, or (ii) athermoplastic polyurethane satisfying the following requirements (a) and(b):

(a) a glass transition temperature when heated from −100° C. at atemperature rising rate of 10° C./min by a differential scanningcalorimeter is −30 to −50° C.; and

(b) JIS A surface hardness is 60-95, the resin composition satisfyingthe following requirements (c) and (d):

(c) a crystallization temperature when heated from room temperature to180° C. at a temperature rising rate of 80° C./min by a differentialscanning calorimeter, maintained at 180° C. for 1 minute, and thencooled at a temperature lowering rate of 10° C./min is 110-170° C.; and

(d) a weight average molecular weight (Mw) in terms of polystyreneconversion when a chloroform soluble component is measured with a gelpermeation chromatography is 100,000-3,000,000.

According to the present invention, there is further provided a methodfor producing a resin composition comprising:

melt mixing 50-99% by weight of a poly-3-hydroxybutyrate polymer, and50-1% by weight of i) a core-shell latex rubber comprising an acrylicrubber and/or a silicone-acrylic rubber copolymer as a core component,and a polymethyl methacrylate as a shell component, or (ii) athermoplastic polyurethane satisfying the following requirements (a) and(b):

(a) a glass transition temperature when heated from −100° C. at atemperature rising rate of 10° C./min by a differential scanningcalorimeter is −30 to −50° C.; and

(b) JIS A surface hardness is 60-95, with an extruder, and

discharging the resulting molten mixture from a die at a molten resintemperature of 160-185° C.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described in detail below.

The poly-3-hydroxybutyrate polymer (hereinafter referred to as “PHBpolymer” for brevity) used in the present invention is described below.

Examples of the PHB polymer that can be used includepoly-3-hydroxybutyrate homopolymers and copolymers of 3-hydroxybutyrateand hydroxyalkanoate other than 3-hydroxybutyrate. Where the PHB polymeris a copolymer, examples of the hydroxyalkanoate other than3-hydroxybutyrate include 3-hydroxypropionate, 3-hydroxyvalerate,3-hydroxyhexanoate, 3-hydroxyheptanoate, 3-hydroxyoctanoate,3-hydroxynonanoate, 3-hydroxydecanoate, 3-hydroxyundecanoate,4-hydroxybutyrate, and hydroxylaurylate. The copolymer is preferablythat the hydroxyalkanoate other than 3-hydroxybutyrate is copolymerizedin an amount of 25 mol % or smaller from the point that a resincomposition having particularly excellent molding processability isobtained.

The PHB polymer preferably used is poly-3-hydroxybutyrate homopolymers,3-hydroxybutyrate/3-hydroxyvalerate copolymers, and3-hydroxybutyrate/4-hydroxybutyrate copolymers from the point that thoseare easily available.

Further, the PHB polymer is preferably produced in microorganisms inthat a resin composition obtained has excellent molding processability.Such PHB polymers are commercially available. Production method of thePHB polymers is disclosed in, for example, U.S. Pat. No. 4,477,654, WO94/11519, and U.S. Pat. No. 5,502,273. The PHB polymers can be producedusing those methods.

The resin composition according to the present invention uses i) acore-shell latex rubber comprising an acrylic rubber and/or asilicone-acrylic rubber copolymer as a core component, and a polymethylmethacrylate as a shell component, or (ii) a thermoplastic polyurethanesatisfying the following requirements (a) and (b):

(a) a glass transition temperature when heated from −100° C. at atemperature rising rate of 10° C./min by a differential scanningcalorimeter is −30 to −50° C.; and

(b) JIS A surface hardness is 60-95.

The core-shell latex rubber comprises an acrylic rubber and/or asilicone-acrylic rubber copolymer as a core component, and a polymethylmethacrylate as a shell component. Use of the core-shell latex rubbercomprising such components results in a resin composition havingexcellent heat resistance and impact resistance.

A method for producing the core-shell latex rubber used in the presentinvention is not particularly limited, and the core-shell latex rubbercan be produced by conducting a multistage emulsion polymerization or amultistage seed polymerization, that is known as a production method ofgeneral core-shell latex rubbers. In such a case, the core componentpreferably has an average particle diameter of 0.05-1 μm from the pointthat a resin composition having excellent impact resistance isparticularly obtained. The core-shell latex rubber used in the presentinvention can be available as commercial products such as METABLENS-2001 (trade name, a product of Mitsubishi Rayon Co.) or METABLENW-450A (trade name, a product of Mitsubishi Rayon Co.).

From that the core-shell latex rubber used in the present inventionenables the resulting resin composition to have further excellent impactresistance, the core-shell latex rubber is preferably that tensilestorage modulus (E′) at measurement temperature of 0° C. and measurementfrequency of 10 Hz is 1-100 MPa, and temperature showing the maximumvalue of loss tangent (tan δ) is −50 to 0° C. In such a case, themaximum value of loss tangent preferably exceeds 0.3 from that the resincomposition obtained has further improved impact resistance. The tensilestorage modulus and loss tangent can be measured with a dynamicviscoelasticity measuring device using a test piece having a thicknessof 0.5-2 mm molded by compression molding.

When a ultrathin cut piece of a compression molded test piece isprepared and is observed with a transmission electron microscope, thecore-shell latex rubber preferably does not form a continuous phase, andthe number of agglomerate having a diameter of 1 μm or larger of thecore-shell latex rubber is preferably less than 2 per 100 μm², from thatthe resin composition obtained using the core-shell latex rubberexhibits excellent impact resistance and heat resistance.

The thermoplastic polyurethane used in the present invention has theproperties that (a) a glass transition temperature when heated from−100° C. at a temperature rising rate of 10° C./min by a differentialscanning calorimeter (hereinafter referred to as “DSC” for brevity) is−30 to −50° C.; and (b) JIS A surface hardness is 60-95. Use of such athermoplastic polyurethane enables the resin composition of the presentinvention to have excellent impact resistance and heat resistance.

The thermoplastic polyurethane used is not particularly limited so longas it is satisfied with the requirements (a) and (b). From that theresin composition obtained has excellent impact resistance, adipicacid-based thermoplastic polyurethane using adipic acid ester as a softsegment, polyether-based thermoplastic polyurethane using polyether,polycaprolactone-based thermoplastic polyurethane usingpolycaprolactone, and polycarbonate-based thermoplastic polyurethaneusing polycarbonate are preferably used, and adipic acid-basedthermoplastic polyurethane using ethylene glycol and/or butylene glycolas adipic acid ester of a soft segment is particularly preferably used.

Such thermoplastic polyurethanes can be available as commercial productssuch as MIRACTRAN E190, MIRACTRAN E385 and MIRACTRAN E585, trade names,products of Nippon Miractran Co., Ltd.

Preferably, a sea-island structure is formed in the resin compositionsuch that the PHB polymer forms a continuous phase and the thermoplasticpolyurethane forms a disperse phase, form that the resin compositionobtained using such a thermoplastic polyurethane exhibits excellent heatresistance. The disperse phase preferably has an average particlediameter of 0.1-3 μm from that further excellent impact resistance isexhibited.

The resin composition according to the present invention comprises50-99% by weight of the PHB polymer and 50-1% by weight of thecore-shell latex rubber or thermoplastic polyurethane, preferably 60-95%by weight of the PHB polymer and 40-5% by weight of the core-shell latexrubber or thermoplastic polyurethane, and more preferably 65-90% byweight of the PHB polymer and 35-10% by weight of the core-shell latexrubber or thermoplastic polyurethane. Where the weight proportion of thecore-shell latex rubber or thermoplastic polyurethane is less than 1% byweight, the resin composition obtained has poor impact resistance. Onthe other hand, where the weight proportion exceeds 50% by weight, theresin composition obtained has poor heat resistance.

The resin composition according to the present invention is satisfiedwith the requirement that a crystallization temperature when heated fromroom temperature to 180° C. at a temperature rising rate of 80° C./minby a differential scanning calorimeter (DSC), maintained at 180° C. for1 minute, and then cooled at a temperature lowering rate of 10° C./minis 110-170° C. The crystallization temperature is preferably 115-160°C., and more preferably 120-150° C. Where the crystallizationtemperature is lower than 110° C., the resin composition obtained haslow crystallization rate, resulting in poor production efficiency whenforming a molded article. On the other hand, the crystallizationtemperature exceeds 170° C., it is practically difficult to form a resincomposition. The crystallization temperature used herein means thehighest temperature in peak temperatures of heat flux based oncrystallization observed when 5 mg of a sample is placed on an aluminumpan, the pan is heated from room temperature to 180° C. at a temperaturerising rate of 80° C./min, the pan is maintained at 1 80° C. for 1minute, and the pan is cooled at a temperature lowering rate of 10°C./min, in measurement by DSC (trade name: DSC-7, a product of PerkinElmer Co.).

The resin composition according to the present invention has a weightaverage molecular weight (hereinafter referred to “Mw” for brevity)100,000-3,000,000, and preferably 120,000-1,000,000, in terms ofpolystyrene conversion when a chloroform soluble component is measuredwith a gel permeation chromatography (hereinafter referred to as “GPC”for brevity). Where Mw is less than 100,000, the resin compositionobtained has poor mechanical strength. On the other hand, where Mwexceeds 3,000,000, the resin composition obtained has poor moldingprocessability. Mw of the chloroform soluble component in resincomposition can be measured by dissolving a resin composition or itsmolded article in chloroform at 60° C. for 2 hours, and measuring amolecular weight of the soluble component obtained. Mw in the presentinvention is measured in a manner such that GPC device equipped with twocolumns (trade name: TSKgel GMHHR-H, a product of Tosoh Corporation) isused, a sample prepared under the conditions of measuring solvent:chloroform, measuring temperature: 40° C., sample dissolving conditions:60° C. and 2 hours, and measuring concentration: 50 mg/50 ml is injectedin an amount of 100 μl, and a column eluation volume is corrected usinga standard polystyrene (a product of Tosoh Corporation).

The resin composition according to the present invention preferablyfurther comprises a phthalic acid-based plasticizer in an amount of0.1-30 parts by weight per 100 parts by weight of the sum of the PHBpolymer, and the core-shell latex rubber or the thermoplasticpolyurethane. Preferable phthalic acid-based plasticizer is a compoundthat lowers a crystalline melting point of the PHB polymer 3° C. ormore. The phthalic acid-based plasticizer used is not particularlylimited, and examples thereof include diethyl phthalate, dibutylphthalate, di-2-ethylhexyl phthalate (DOP), dibutylbenzyl phthalate, anddimethylcylohexyl phthalate. Those may be used alone or as mixtures oftwo or more thereof.

The resin composition can have the form such as pellet form, powder formor bulk form. Of those, pellet form is preferable from the standpointsof excellent production efficiency in its production and excellenthandleability in molding processing. Examples of a method of forming apellet form include a strand cut method which cuts strand-shaped moltengranulates with a strand cutter, an underwater cut method which cuts amolten resin in water, a hot cut method which cuts a molten resindirectly or after cooling the same with, for example, mist, and a sheetpalletizing method which cuts sheet-like molten granulates with a sheetpelletizer. Of those, the strand cut method, underwater cut method andhot cut method are preferably used in that pellets having good intermeshof a resin in extrusion molding are obtained.

The production method of the resin composition of the present inventioncan use any method and apparatus so long as the PHB polymer, and thecore-shell latex rubber or the thermoplastic polyurethane can be mixed.Of those methods, a production method of using a kneader in whichtemperature of a molten resin discharged from a die of an extruder isset to 160-185° C. is preferably used from the standpoint that a resincomposition having excellent molding processability is obtained. Thekneader used is not particularly limited, and examples of the kneaderinclude a co-rotating twin-screw extruder, a counter-rotating twin-screwextruder such as a conical twin-screw extruder, a batch type mixer suchas Banbury mixer or a pressure kneader, and a roll kneader. Of those, acounter-rotating twin-screw extruder equipped with a strong kneadingtype screw such as kneading disc is preferably used from the standpointthat a composition showing excellent impact resistance and heatresistance is obtained.

In producing the resin composition of the present invention, the PHBpolymer, and the core-shell latex rubber or the thermoplasticpolyurethane are desirably dried beforehand. The drying conditions arenot particularly limited. For example, in molding and processing theresin composition of the present invention, the resin composition isdesirably dried beforehand. The drying conditions are optional, and forexample, the resin composition is preferably dried at a temperature of40-90° C. for about 30 minutes to about 3 days.

A method for molding the resin composition of the present invention isnot particularly limited, and examples of the molding method includeodd-shaped extrusion molding, film molding, sheet molding, blow molding,injection molding, expansion molding, extrusion coating, and rotarymolding. Of those, the preferable method is injection molding. Inconducting the injection molding, when temperature of a molten resin is230° C. or lower, preferably 210° C. or lower, time required forcrystallization in a mold becomes short, making it possible to shortenmolding cycle.

The resin composition of the present invention may contain fillers. Thefillers added are not particularly limited. Examples of the filler addedinclude inorganic fillers such as calcium carbonate, mica, talc, silica,barium sulfate, calcium sulfate, kaolin, clay, pyroferrite, bentonite,serisanite, zeolite, nepheline syenite, attapulgite, wollastonite,ferrite, calcium silicate, magnesium carbonate, dolomite, antimonytrioxide, titanium oxide, iron oxide, molybdenum disulfide, graphite,gypsum, glass beads, glass balloons, glass fibers, quartz, quartz glassor montmorillonite; various plant fibers such as starch, cellulosefibers or kenaf; natural polymers such as wood powders, bean curdrefuse, chaff or bran; and organic fillers such as modified products ofthose natural polymers.

Of those, calcium carbonate and talc have the function to increasecrystallization rate, and therefore are preferably used. Talc isparticularly preferably used. To increase dispersibility of the fillersinto the resin composition, surface-modified calcium carbonate, talc andclay can be used. Where the fillers are used, the fillers are preferablyused in an amount of 100 parts by weight or less per 100 parts by weightof the resin composition, so that the resin composition having excellentbalance in rigidity and impact resistance is obtained.

The resin composition of the present invention may further contain fattyacids, fatty acid esters, aliphatic amides and fatty acid metal salts.

If required and necessary, the resin composition may further containcrystal nucleating agents. By this addition, crystal growing rate isfurther increased. Examples of the crystal nucleating agent includeboron nitride, mica, talc, alumina, calcium hydroxyapatite, aluminumchloride and clay. Of those, talc or boron nitride is preferably used.

If required and necessary, the resin composition may further containhydrolysis inhibitors represented by carbodiimide, antiblocking agents,release agents, antistatic agents, slip agents, antifogging agents,lubricants, heat stabilizers, ultraviolet stabilizers, lightstabilizers, mildew-proofing agents, rust-proofing agents, ion-trappingagents, foaming agents, flame retardants, flame retardant aids or thelike. Further, other thermoplastic resins or rubbers, particularlythermoplastic resins called biodegradable resins, may be blended withthe resin composition of the present invention.

The resin composition of the present invention is suitably used forhousing or structure parts of appliances; automobile exterior parts suchas bumper, rocker laces, side laces or overfender; automobile interiorparts such as carpets, head liners, door trims or sun visors; and thelike.

The resin composition of the present invention has excellent heatresistance and impact resistance, and is therefore useful as variousmolding materials.

The present invention is described in more detail by reference to thefollowing examples, but it should be understood that the invention isnot construed as being limited thereto.

Measurement methods used in the Examples and Comparative Examples aredescribed below.

Measurement of Crystallization Temperature

Crystal growth rate was measured using a differential scanningcalorimeter (trade name: DSC-7, a product of Perkin Elmer Co.). 5 mg ofa sample was cut from a pellet, and placed on an aluminum pan. The panwas heated from room temperature to 180° C. at a temperature rising rateof 80° C./min, and was maintained at 180° C. for 1 minute. The pan wasthen cooled at a temperature lowering rate of 10° C./min. The highesttemperature in peak temperatures of heat flux based on crystallizationwas designated as the crystallization temperature.

Measurement of Crystalline Melting Point

Crystalline melting point was measured using a differential scanningcalorimeter (trade name: DSC-7, a product of Perkin Elmer Co.). 5 mg ofa sample was cut from a pellet, and placed on an aluminum pan. Thehighest temperature in peak temperatures of heat flux based on crystalmelting observed when the pan was heated from room at a temperaturerising rate of 10° C./min was designated as the crystalline meltingpoint.

Measurement of Weight Average Molecular Weight

Pellets obtained by granulation were dissolved in chloroform at 60° C.Using a soluble component alone thus obtained, molecular weight wasmeasured with a gel permeation chromatography. The molecular weight thusmeasured was corrected using a standard polystyrene (a product of TosohCorporation) to determine a weight average molecular weight (Mw) interms of polystyrene conversion. The measurement conditions were asfollows.

Device: trade name: HLC8020GPC (a product of Tosoh Corporation)

Solvent: chloroform

Sample dissolving conditions: 60° C., 2 hours

Temperature: 40° C.

Measurement concentration: 50 mg/50 ml

Injection amount: 100 μl

Column: trade name: TSKgel GMHHR-H (a product of Tosoh Corporation); twocolumns were used.

Measurement of Linear Viscoelasticity of Core-Shell Latex Rubber

Temperature dependence of dynamic tensile modulus was measured attensile mode using a solid viscoelasticity measuring device (trade name:DVE-V4, a product of Rheology Co.). A core-shell latex rubber platemolded in 1 mm thickness with a compression molding machine was cut intoa size having a width of 5 mm and a length of 20 mm to obtain testpiece. Measuring frequency of liner viscoelasticity was 10 Hz, atemperature rising rate was 2° C./min, and measurement temperatureregion was from −100° C. to 100° C. Sinusoidal strain was applied attensile mode. Loss tangent (tan δ) was measured in a range of from −100°C. to 50° C. Tensile storage modulus (E′) was also measured at 0° C.

Measurement of Glass Transition Temperature of ThermoplasticPolyurethane

Glass transition temperature of thermoplastic polyurethane was measuredusing a differential scanning calorimeter (trade name: DSC-7, a productof Perkin Elmer Co.). 5 mg of a sample was cut from a pellet, and placedon an aluminum pan. The pan was heated from −100° C. at a temperaturerising rate of 10° C./min to measure the glass transition temperature.

Measurement of Surface Hardness of Thermoplastic Polyurethane

JIS A surface hardness of a thermoplastic polyurethane was measured at0° C. according to JIS K7311.

Measurement of Izod Impact Strength

Using a notched Izod test piece obtained by injection molding, Izodimpact strength was measured at 23° C. according to ASTM D256. Impactwas applied from a notch side. Injection molding was conducted using aninjection molding machine (trade name: IS 100E, a product of ToshibaMachine Plastics Engineering Co.) under the conditions of nozzletemperature: 175° C., injection time: 10 seconds and mold temperature:60° C.

Observation of Phase Structure

A resin composition was compression molded under the conditions ofheating temperature: 180° C., pressure: 10 MPa, heating time: 3 minutesand cooling temperature: 60° C. to obtain a test piece having athickness of 1 mm. This compression molded test piece was cut into anultrathin cut piece with an untramicrotome. The cut piece was dyed withruthenic acid, and observed with a transmission electron microscope(trade name: JEM-2000FX, a product of JEOL Co.).

In case of a resin composition using a core-shell latex rubber, thenumber of agglomerates having a diameter exceeding 1 μm in a core-shelllatex rubber present on an optionally selected visual field of 10 μm×10μm was counted. Further, continuous phase was observed with aphotomicrograph.

In case of a resin composition using a thermoplastic polyurethane, phasestructure of a polyurethane and particle diameter of a disperse phasewere observed with a photomicrograph.

Measurement of Heat Resistance

Using an injection molded test piece, Vicat softening temperature wasmeasured according to JIS K7206.

EXAMPLE 1

70% by weight of poly-3-hydroxybutyrate (trade name: Biocycle 1000, aproduct of PHB Industrial S/A) which had previously been pre-dried in anoven at 80° C. for 4 hours, and 30% by weight of a core-shell latexrubber comprising polymethyl methacrylate as a shell component andacrylic rubber as a core component (trade name: METABLEN W-450A, aproduct of Mitsubishi Rayon Co.) were melt extrusion mixed with acounter- rotating twin-screw extruder equipped with circular die (tradename: LABOPLAST MILL, a product of Toyo Seiki Seisakusho, resintemperature: 178° C., number of revolution: 100 rpm, use of stronglykneading type screw). An extruded strand obtained was solidified in ahot bath set at 60° C. The resulting solid strand was palletized with astrand cutter to obtain a resin composition in pellet form.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, the number of agglomerates having a diameterexceeding 1 μm of a core-shell latex rubber present on an optionallyselected visual field of 10 μm×10 μm was counted by a transmissionelectron microscope observation using a compression molded test piece.The results obtained are shown in Table 1 below.

Further, dynamic viscoelasticity was measured using a test pieceobtained by compression molding a core-shell latex rubber alone at 180°C. The measurement results obtained are shown in Table 2 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and thus had excellent heat resistance and impactresistance.

EXAMPLE 2

A resin composition in a pellet form was obtained in the same manner asin Example 1 above, except that 10 parts by weight of di-2-ethylhexylphthalate (DOP) were added to 100 parts by weight of the mixture of 70%by weight of poly-3-hydroxybutyrate and 30% by weight of the core-shelllatex rubber as used in Example 1.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, the number of agglomerates having a diameterexceeding 1 μm of a core-shell latex rubber present on an optionallyselected visual field of 10 μm×10 μm was counted by a transmissionelectron microscope observation using a compression molded test piece.The results obtained are shown in Table 1 below.

Further, dynamic viscoelasticity was measured using a test pieceobtained by compression molding a core-shell latex rubber alone at 180°C. The measurement results obtained are shown in Table 2 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and excellent heat resistance and impactresistance.

EXAMPLE 3

A resin composition in a pellet form was obtained in the same manner asin Example 1 above, except that a core-shell latex rubber in which acore component is a silicone-acrylic rubber copolymer, and a shellcomponent is polymethyl methacrylate (trade name: METABLEN S-2001, aproduct of Mitsubishi Rayon Co.) was used in place of a core-shell latexrubber (trade name: METABLEN W-450A, a product of Mitsubishi Rayon Co.).

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, the number of agglomerates having a diameterexceeding 1 μm of a core-shell latex rubber present on an optionallyselected visual field of 10 μm×10 μm was counted by a transmissionelectron microscope observation using a compression molded test piece.The results obtained are shown in Table 1 below.

Further, dynamic viscoelasticity was measured using a test pieceobtained by compression molding a core-shell latex rubber alone at 180°C. The measurement results obtained are shown in Table 2 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and excellent heat resistance and impactresistance.

EXAMPLE 4

A resin composition in a pellet form was obtained in the same manner asin Example 3 above, except that 10 parts by weight of ethyl phthalate(DEP) were added to 100 parts by weight of the mixture of 70% by weightof poly-3-hydroxybutyrate and 30% by weight of the core-shell latexrubber.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, the number of agglomerates having a diameterexceeding 1 μm of a core-shell latex rubber present on an optionallyselected visual field of 10 μm×10 μm was counted by a transmissionelectron microscope observation using a compression molded test piece.The results obtained are shown in Table 1 below.

Further, dynamic viscoelasticity was measured using a test pieceobtained by compression molding a core-shell latex rubber alone at 180°C. The measurement results obtained are shown in Table 2 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and excellent heat resistance and impactresistance.

EXAMPLE 5

A resin composition in a pellet form was obtained in the same manner asin Example 4 above, except that 10 parts by weight of talc (trade name:MICRO ACE P-3, surface epoxy-modified: 1%, a product of Nippon Talc Co.)were added to 100 parts by weight of the mixture of 70% by weight ofpoly-3-hydroxybutyrate and 30% by weight of the core-shell latex rubber.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, the number of agglomerates having a diameterexceeding 1 μm of a core-shell latex rubber present on an optionallyselected visual field of 10 μm×10 μm was counted by a transmissionelectron microscope observation using a compression molded test piece.The results obtained are shown in Table 1 below.

Further, dynamic viscoelasticity was measured using a test pieceobtained by compression molding a core-shell latex rubber alone at 180°C. The measurement results obtained are shown in Table 2 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and excellent heat resistance and impactresistance.

EXAMPLE 6

A resin composition in a pellet form was obtained in the same manner asin Example 3 above, except that a counter-rotating twin-screw extruderequipped with full-flighted screw was used in place of thecounter-rotating twin screw extruder equipped with strongly kneadingtype screw.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, the number of agglomerates having a diameterexceeding 1 μm of a core-shell latex rubber present on an optionallyselected visual field of 10 μm×10 μm was counted by a transmissionelectron microscope observation using a compression molded test piece.The results obtained are shown in Table 1 below.

Further, dynamic viscoelasticity was measured using a test pieceobtained by compression molding a core-shell latex rubber alone at 180°C. The measurement results obtained are shown in Table 2 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and excellent heat resistance and impactresistance.

EXAMPLE 7

A resin composition in a pellet form was obtained in the same manner asin Example 1 above, except that a core-shell latex rubber in which acore component is a silicone-acrylic rubber copolymer, and a shellcomponent is polymethyl methacrylate (trade name: METABLEN SRK200, aproduct of Mitsubishi Rayon Co.) was used in place of a core-shell latexrubber (trade name: METABLEN W-450A, a product of Mitsubishi Rayon Co.).

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, the number of agglomerates having a diameterexceeding 1 μm of a core-shell latex rubber present on an optionallyselected visual field of 10 μm×10 μm was counted by a transmissionelectron microscope observation using a compression molded test piece.The results obtained are shown in Table 1 below.

Further, dynamic viscoelasticity was measured using a test pieceobtained by compression molding a core-shell latex rubber alone at 180°C. The measurement results obtained are shown in Table 2 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and excellent heat resistance and impactresistance.

COMPARATIVE EXAMPLE 1

Pellets were obtained in the same manner as in Example 1, except thatextrusion was conducted using poly-3-hydroxybutyrate (trade name:Biocycle 1000, a product of PHB Industrial S/A) alone.

The pellets obtained were measured for crystallization temperature,crystalline melting temperature, and average molecular weight of achloroform-soluble component. Further, Izod impact strength and Vicatsoftening temperature were measured using an injection molded testpiece. The results obtained are shown in Table 1 below.

The resin obtained had low Izod impact strength, and thus had poorimpact resistance.

COMPARATIVE EXAMPLE 2

A resin composition in a pellet form was obtained in the same manner asin Example 1 above, except that a core-shell latex rubber in which acore component is a styrene-butadiene copolymer rubber, and a shellcomponent is polymethyl methacrylate (trade name: METABLEN C-223A, aproduct of Mitsubishi Rayon Co.) was used in place of a core-shell latexrubber (trade name: METABLEN W-450A, a product of Mitsubishi Rayon Co.).

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, the number of agglomerates having a diameterexceeding 1 μm of a core-shell latex rubber present on an optionallyselected visual field of 10 μm×10 μm was counted by a transmissionelectron microscope observation using a compression molded test piece.The results obtained are shown in Table 1 below.

Further, dynamic viscoelasticity was measured using a test pieceobtained by compression molding a core-shell latex rubber alone at 180°C. The measurement results obtained are shown in Table 2 below.

The resin composition obtained had low Izod impact strength, and thushad poor impact resistance.

COMPARATIVE EXAMPLE 3

A resin composition in a pellet form was obtained in the same manner asin Example 1 above, except that the resin temperature immediately afterdischarge from the counter-rotating twin-screw extruder was changed 250°C. in place of 178° C.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, the number of agglomerates having a diameterexceeding 1 μm of a core-shell latex rubber present on an optionallyselected visual field of 10 μm×10 μm was counted by a transmissionelectron microscope observation using a compression molded test piece.The results obtained are shown in Table 1 below.

Further, dynamic viscoelasticity was measured using a test pieceobtained by compression molding a core-shell latex rubber alone at 180°C. The measurement results obtained are shown in Table 2 below.

The resin composition obtained had low crystallization temperature of92° C., resulting in poor molding processability, and also had low Izodimpact strength, thus having poor impact resistance.

COMPARATIVE EXAMPLE 4

A resin composition in a pellet form was obtained in the same manner asin Example 1 above, except that 30% by weight of poly-3-hydroxybutyrateand 70% by weight of the core-shell latex rubber were used in place of70% by weight of poly-3-hydroxybutyrate and 30% by weight of thecore-shell latex rubber.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, the number of agglomerates having a diameterexceeding 1 μm of a core-shell latex rubber present on an optionallyselected visual field of 10 μm×10 μm was counted by a transmissionelectron microscope observation using a compression molded test piece.The results obtained are shown in Table 1 below.

Further, dynamic viscoelasticity was measured using a test pieceobtained by compression molding a core-shell latex rubber alone at 180°C. The measurement results obtained are shown in Table 2 below.

The resin composition obtained had low Vicat softening temperature of70° C., and thus had poor heat resistance. TABLE 1 Properties of resinWeight Vicat Izod Number of Crystallization Crystalline AverageSoftening Impact Agglomerates Temperature Melting Molecular TemperatureStrength Continuous (per 100 (° C.) Point (° C.) Weight (° C.) (J/m)Phase* μm²) Example 1 137 177 370000 163 105 PHB 0 Example 2 133 172420000 161 125 PHB 0 Example 3 136 177 370000 164 90 PHB 0 Example 4 130169 440000 163 125 PHB 0 Example 5 132 171 420000 165 75 PHB 0 Example 6137 177 370000 160 70 Co-continuous 8 Example 7 137 178 370000 163 70PHB 0 Comparative 136 177 370000 165 30 PHB — Example 1 Comparative 137177 370000 163 45 PHB 0 Example 2 Comparative 92 175 68000 159 40 PHB 12Example 3 Comparative 137 176 370000 70 >200 Latex >20 Example 4*PHB: Polyhydroxybutyrate polymer is continuous phase.Latex: Core-shell latex rubber is continuous phase.

TABLE 2 Properties of core-shell latex rubber Peak Temperature StorageMaximum Value of Loss Elasticity of Loss Tangent Shell Component CoreComponent Tangent at 0° C. at −50 to 0° C. Examples 1-2 Methylmethacrylate Acrylic rubber −31 55 0.51 Examples 3-6 Methyl methacrylateSilicone-acrylic rubber −32 50 0.50 Example 7 Methyl methacrylateSilicone-acrylic rubber −30 480 0.23 Comparative Methyl methacrylateStyrene-butadiene rubber −71 195 0.30 Example 2 Comparative Methylmethacrylate Acrylic rubber −31 55 0.51 Examples 3-4

EXAMPLE 8

70% by weight of poly-3-hydroxybutyrate (trade name: Biocycle 1000, aproduct of PHB Industrial S/A) which had previously be pre-dried in anoven at 80° C. for 4 hours, and 30% by weight of an adipic acid-basedthermoplastic polyurethane (trade name: MIRACTRAN E190, a product ofNippon Miractran Co., Ltd.) were melt extrusion mixed with a counter-rotating twin-screw extruder equipped with circular die (trade name:LABOPLAST MILL, a product of Toyo Seiki Seisakusho, resin temperature:178° C., number of revolution: 100 rpm, use of strongly kneading typescrew). An extruded strand obtained was solidified in a hot bath set at60° C. The resulting sold strand was palletized with a strand cutter toobtain a resin composition in pellet form.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, a transmission electron microscope observationwas conducted using a compression molded test piece. The resultsobtained are shown in Table 3 below.

Further, glass transition temperature and surface hardness of thethermoplastic polyurethane alone are shown in Table 4 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and thus had excellent heat resistance and impactresistance.

EXAMPLE 9

A resin composition in a pellet form was obtained in the same manner asin Example 8 above, except that 10 parts by weight of di-2-ethylhexylphthalate (DOP) were added to 100 parts by weight of the mixture of 70%by weight of poly-3-hydroxybutyrate and 30% by weight of the adipicacid-based thermoplastic polyurethane.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, a transmission electron microscope observationwas conducted using a compression molded test piece. The resultsobtained are shown in Table 3 below.

Further, glass transition temperature and surface hardness of thethermoplastic polyurethane alone are shown in Table 4 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and thus had excellent heat resistance and impactresistance.

EXAMPLE 10

A resin composition in a pellet form was obtained in the same manner asin Example 8 above, except that 10 parts by weight of talc (trade name:MICRO ACE P-3, surface epoxy-modified: 1%, a product of Nippon Talc Co.)were added to 100 parts by weight of the mixture of 70% by weight ofpoly-3-hydroxybutyrate and 30% by weight of the adipic acid-basedthermoplastic polyurethane.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, a transmission electron microscope observationwas conducted using a compression molded test piece. The resultsobtained are shown in Table 3 below.

Further, glass transition temperature and surface hardness of thethermoplastic polyurethane alone are shown in Table 4 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and thus had excellent heat resistance and impactresistance.

EXAMPLE 11

A resin composition in a pellet form was obtained in the same manner asin Example 8 above, except that a polycaprolacton-based thermoplasticpolyurethane (trade name: MIRACTRAN E585, a product of Nippon MiractranCo., Ltd.) was used in place of the adipic acid-based thermoplasticpolyurethane (trade name: MIRACTRAN E190, a product of Nippon MiractranCo., Ltd.)

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, a transmission electron microscope observationwas conducted using a compression molded test piece. The resultsobtained are shown in Table 3 below.

Further, glass transition temperature and surface hardness of thethermoplastic polyurethane alone are shown in Table 4 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and thus had excellent heat resistance and impactresistance.

EXAMPLE 12

A resin composition in a pellet form was obtained in the same manner asin Example 8 above, except that an adipic acid-based thermoplasticpolyurethane having different diol component (trade name: MIRACTRANE685, a product of Nippon Miractran Co., Ltd.) was used in place of theadipic acid-based thermoplastic polyurethane (trade name: MIRACTRANE190, a product of Nippon Miractran Co., Ltd.)

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection testpiece. In addition, a transmission electron microscope observation wasconducted using a compression molded test piece. The results obtainedare shown in Table 3 below.

Further, glass transition temperature and surface hardness of thethermoplastic polyurethane alone are shown in Table 4 below.

The resin composition obtained had high Vicat softening temperature andIzod impact strength, and thus had excellent heat resistance and impactresistance.

COMPARATIVE EXAMPLE 5

A resin composition in a pellet form was obtained in the same manner asin Example 8 above, except that a polyether-based thermoplasticpolyurethane (trade name: MIRACTRAN E385, a product of Nippon MiractranCo., Ltd.) was used in place of the adipic acid-based thermoplasticpolyurethane (trade name: MIRACTRAN E190, a product of Nippon MiractranCo., Ltd.)

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, a transmission electron microscope observationwas conducted using a compression molded test piece. The resultsobtained are shown in Table 3 below.

Further, glass transition temperature and surface hardness of thethermoplastic polyurethane alone are shown in Table 4 below.

The resin composition obtained had low Izod impact strength, and thushad poor impact resistance.

COMPARATIVE EXAMPLE 6

A resin composition in a pellet form was obtained in the same manner asin Example 8 above, except that a different adipic acid-basedthermoplastic polyurethane (trade name: MIRACTRAN E198, a product ofNippon Miractran Co., Ltd.) was used in place of the adipic acid-basedthermoplastic polyurethane (trade name:. MIRACTRAN E190, a product ofNippon Miractran Co., Ltd.)

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, a transmission electron microscope observationwas conducted using a compression molded test piece. The resultsobtained are shown in Table 3 below.

Further, glass transition temperature and surface hardness of thethermoplastic polyurethane alone are shown in Table 4 below.

The resin composition obtained had low Izod impact strength, and thushad poor impact resistance.

COMPARATIVE EXAMPLE 7

A resin composition in a pellet form was obtained in the same manner asin Example 8 above, except that the resin temperature immediately afterdischarge from the counter-rotating twin-screw extruder was changed 250°C. in place of 178° C.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, a transmission electron microscope observationwas conducted using a compression molded test piece. The resultsobtained are shown in Table 3 below.

Further, glass transition temperature and surface hardness of thethermoplastic polyurethane alone are shown in Table 4 below.

The resin composition obtained had low Izod impact strength, and thushad poor impact resistance.

COMPARATIVE EXAMPLE 8

A resin composition in a pellet form was obtained in the same manner asin Example 8 above, except that 30% by weight of poly-3-hydroxybutyrateand 70% by weight of the thermoplastic polyurethane were used in placeof 70% by weight of poly-3-hydroxybutyrate and 30% by weight of thethermoplastic polyurethane.

The resin composition obtained was measured for crystallizationtemperature, crystalline melting temperature, and average molecularweight of a chloroform-soluble component. Further, Izod impact strengthand Vicat softening temperature were measured using an injection moldedtest piece. In addition, a transmission electron microscope observationwas conducted using a compression molded test piece. The resultsobtained are shown in Table 3 below.

Further, glass transition temperature and surface hardness of thethermoplastic polyurethane alone are shown in Table 4 below.

The resin composition obtained had low Vicat softening temperature of68° C., and thus had poor heat resistance. TABLE 3 Properties of resinAverage Particle Weight Vicat Izod Diameter of CrystallizationCrystalline Average Softening Impact Disperse Temperature MeltingMolecular Temperature Strength Continuous Phase (° C.) Point (° C.)weight (° C.) (J/m) Phase* (μm) Example 8 137 177 370000 164 400 PHB 1Example 9 133 172 420000 162 440 PHB 1 Example 10 135 176 400000 156 320PHB 1 Example 11 136 176 360000 163 80 PHB 0.5 Example 12 137 177 380000163 70 PHB 1.5 Comparative 136 177 370000 165 40 PHB 2 Example 5Comparative 137 177 350000 164 45 PHB 1 Example 6 Comparative 91 17569000 159 40 PHB 5 Example 7 Comparative 137 174 370000 68 >500 TPU —Example 8*PHB: Polyhydroxybutyrate polymer is continuous phase.TPU: Thermoplastic polyurethane is continuous phase.

TABLE 4 Properties of thermoplastic polyurethane Glass SurfaceTransition Hardness Temperature Soft Segment JIS A (° C.) Examples 8-10Adipic acid polyester 90 −43 Diol component: ethylene glycol, butylenesglycol Example 11 Polycaprolactone 85 −48 Example 12 Adipic acidpolyester 85 −48 Diol component: pentane diol Comparative Polyether 85−58 Example 5 Comparative Adipic acid polyester 98 −39 Example 6 Diolcomponent: ethylene glycol, butylene glycol Comparative Adipic acidpolyester 90 −43 Examples 7-8 Diol component: ethylene glycol, butyleneglycol

It should further be apparent to those skilled in the art that variouschanges in form and detail of the invention as shown and described abovemay be made. It is intended that such changes be included within thespirit and scope of the claims appended hereto.

This application is based on Japanese Patent Application No. 2004-328804filed Nov. 12, 2004, the disclosure of which is incorporated herein byreference in its entirety.

1. A resin composition comprising: 50-99% by weight of apoly-3-hydroxybutyrate polymer, and 50-1% by weight of i) a core-shelllatex rubber comprising an acrylic rubber and/or a silicone-acrylicrubber copolymer as a core component, and a polymethyl methacrylate as ashell component, or (ii) a thermoplastic polyurethane satisfying thefollowing requirements (a) and (b): (a) a glass transition temperaturewhen heated from −100° C. at a temperature rising rate of 10° C./min bya differential scanning calorimeter is −30 to −50° C.; and (b) JIS Asurface hardness is 60-95, the resin composition satisfying thefollowing requirements (c) and (d): (c) a crystallization temperaturewhen heated from room temperature to 180° C. at a temperature risingrate of 80° C./min by a differential scanning calorimeter, maintained at180° C. for 1 minute, and then cooled at a temperature lowering rate of10° C./min is 110-170° C.; and (d) a weight average molecular weight(Mw) in terms of polystyrene conversion when a chloroform solublecomponent is measured with a gel permeation chromatography is100,000-3,000,000.
 2. The resin composition as claimed in claim 1,further comprising a phthalic acid-based plasticizer in an amount of0.1-30 parts by weight per 100 parts by weight of the sum of thepoly-3-hydroxybutyrate polymer, and the core-shell latex rubber or thethermoplastic polyurethane.
 3. The resin composition as claimed in claim1, wherein the core-shell latex rubber is that tensile storage modulus(E′) at measurement temperature of 0° C. and measurement frequency of 10Hz is 1-100 MPa, and temperature showing the maximum value of losstangent (tan δ) is −50 to 0° C.
 4. The resin composition as claimed inclaim 1, wherein when a ultrathin cut piece of a compression moldingtest piece is prepared and is observed with a transmission electronmicroscope, the core-shell latex rubber does not form a continuousphase, and the number of agglomerate having a diameter of 1 μm or largerof the core-shell latex rubber is less than 2 per 100 μm².
 5. The resincomposition as claimed in claim 1, wherein the thermoplasticpolyurethane is an adipic acid-based thermoplastic polyurethane.
 6. Theresin composition as claimed in claim 1, wherein the thermoplasticpolyurethane is at least one member selected from the group consistingof polyether-based thermoplastic polyurethane, polycaprolactone-basedthermoplastic polyurethane, and polycarbonate-based thermoplasticpolyurethane.
 7. The resin composition as claimed in claim 1, whereinwhen an ultrathin cut piece of a compression molded test piece of theresin composition is observed with a transmission electron microscope, asea-island structure is formed such that the poly-3-hydroxybutyratepolymer forms a continuous phase and the thermoplastic polyurethaneforms a disperse phase, and the disperse phase has an average particlediameter of 0.1-3 μm.
 8. A method for producing a resin compositioncomprising: melt mixing 50-99% by weight of a poly-3-hydroxybutyratepolymer, and 50-1% by weight of i) a core-shell latex rubber comprisingan acrylic rubber and/or a silicone-acrylic rubber copolymer as a corecomponent, and a polymethyl methacrylate as a shell component, or (ii) athermoplastic polyurethane satisfying the following requirements (a) and(b): (a) a glass transition temperature when heated from −100° C. at atemperature rising rate of 10° C./min by a differential scanningcalorimeter is −30 to −50° C.; and (b) JIS A surface hardness is 60-95,with an extruder, and discharging the resulting molten mixture from adie at a molten resin temperature of 160-185° C.